When foreign substances such as dust or finger prints adhere to the surface of an information medium for recording user information signals, the recording properties of the information medium is greatly varied. Accordingly, it is usual to store the information medium within a cartridge in order to guarantee stable recording.
The main elements of the cartridge are: a medium storage section for storing an information medium within a case member obtained by integrating an upper half and a lower half; a window section for exposing a part of the stored information medium; a shutter member for opening/closing the window section; and a shutter pressing section for restricting the separation of the shutter member from the cartridge.
For example, in order to produce a cartridge for an magneto-optical recording medium or a phase-change-type write-once recording medium which is generally called “write-once”, the case member, the shutter member and the shutter pressing section are formed individually, and then the shutter member is incorporated into the case member after the medium is stored within the case member, and then the shutter pressing section is attached to the case member by thermal fusion or adhesion. Thus, the shutter member is configured to appropriately operate the opening/closing operation.
In such a cartridge for the magneto-optical recording medium or a phase-change-type write-once medium, it is essentially necessary that the shutter member and the case member are formed as separate members so that the shutter member can slide on the case member. When the case member and the shutter pressing section are formed as separate members, the number of parts required for the cartridge is increased, and the number of steps required for producing the cartridge is increased due to the additional step of attaching the shutter pressing section to the case member. As a result, the cost of the cartridge is increased.
In general, the medium is stored within the medium storage section, and then the case member is assembled by integrating the upper half and the lower half. Then, the shutter pressing section is attached to the case member after the shutter member engages with the case member such that the shutter member can slide on the case member. Accordingly, the step of attaching the shutter pressing section to the case member is the final step.
However, the shutter pressing section may be attached to the case member such that the direction of the shutter pressing section is not parallel to the sliding direction of the shutter member. When the shutter pressing section is attached to the case member by using an adhesive, too much adhesive may cause the shutter member to be adhered to the case member and too little adhesive may cause insufficient adhesion. When the shutter pressing section is attached to the case member by using thermal fusion, the case member may be distorted during the fusion step. These problems may adversely effect the functioning of the cartridge. This causes low efficiency of the work and increase of the cost of the cartridge due to increase of the cost of materials.
In order to solve the problems described above, a method is proposed for integrally forming the shutter pressing section during the producing process of the upper half and the lower half. Recently, such a method is applied to most cartridges. In this method, the case member is made of resin and the upper half and the lower half are formed by using the injection molding process.
Reference 1 discloses a technique for integrally forming the shutter pressing section during the injection molding process.
FIGS. 9 to 11 are plan views illustrating the structure of the cartridge disclosed in Reference 1. In this example, the cartridge is a rewritable digital versatile disc cartridge (hereafter, simply referred to as a cartridge). The cartridge includes a shutter member 100 and a case member 200.
The shutter member 100 includes a sliding section 101 which slides on a sidewall of the case member 200; a shutter opener engagement section 102 which engages with a shutter opener (not shown) for sliding the shutter member 100; a window opening/closing section 103 which opens/closes a window section formed in the case member 200; and an eaves engagement section 104 which engages with the shutter pressing section.
The case member 200 includes: a sliding sidewall 201 which engages with the sliding section 101 of the shutter member 100 such that the sliding section 101 slides on the sliding sidewall 201; a rear sidewall 203 which is opposite to the sliding sidewall 201 across the window section 202; a pair of lateral sidewalls 204 connected to the sliding sidewall 201 and the rear sidewall 203; an upper case section 205 having a space defined by the rear sidewall 203 and the pair of lateral sidewalls 204; a lower case section 206 on which the window opening/closing section 103 slides, wherein a gap having a thickness which is substantially equal to the thickness of 103 is provided between the upper case section 205 and the lower case section 206; a boundary section 208 which defines a boundary between the upper case section 205 and the lower case section 206, wherein a step portion 207 is formed at the boundary such that the step portion 207 extends in a direction which is substantially parallel to the rear sidewall 203; a pair of open position regulating sections 209 which regulates the open range of the shutter member 100 by step portions, wherein the step portions are formed between the upper case section 205 and the lower case section 206 along the lateral sidewalls 204; an eaves section 210 which extends from the upper case section 205, for engaging with the eaves engagement section 104 of the shutter member 100; a medium storage section 211 for storing an information medium 300; a slide rib 212 which engages with the sliding section 101 of the shutter member 100 to guide the sliding of the sliding section 101; an alignment hole 213 having a prolonged shape and an alignment hole 214 having a circular shape, both of which engage with pins used in determining the position of the cartridge on a tray on which the cartridge is placed during a recording/reproduction operation of the recording/reproduction device.
The window section 202 includes: a rotation means entry portion 215 which allows a medium rotation driving means (not shown) for driving the rotation of the information medium 300 to be entered into the cartridge; and a head entry portion 216 which allows a head for sending/receiving user information signals for an information layer (not shown) of the information medium 300 to be entered into the cartridge.
The shutter pressing section 217 is formed by the eaves section 210 which engages with the eaves engagement section 104 of the shutter member 100; and the step portion 207 at the boundary section 208 within a range where the eaves section 210 extends along the boundary section 208 between the upper case section 205 and the lower case section 206.
Next, the shutter opening operation of the cartridge disclosed in Reference 1 will be described.
FIG. 9 is a plan view illustrating a cartridge in a state where the shutter member 100 closes the window section 202. In this state, the eaves section 210 is configured to completely cover the eaves engagement section 104. From this state, the shutter member 100 is moved in a direction (e.g. a direction toward the right side of the drawing sheet) while the shutter opener engages with the shutter opener engagement section 102, the window opening/closing section 103 slides on a surface of the lower case section 206. Thus, the window section 202 goes into an open state. As shown in FIG. 10, the window section 202 includes the rotation means entry portion 215 and the head entry portion 216.
The eaves section 210 engages with the eaves engagement section 104. This makes it possible to restrict the separation of the window opening/closing section 103 from the lower case section 206 and to guide the window opening/closing section 103.
The case member 200 and the eaves section 210 are integrally formed by the injection molding process, so that the case member 200 includes the eaves section 210. As a result, a projection plane obtained by projecting the eaves section 210 onto the lower case section 206 (i.e. a portion of the lower case section 206 positioned immediately below the eaves section 210) has an opening 218 which is bored through the lower case section 206 in a direction towards the information medium 300.
When the shutter member 100 is further moved in the direction toward the right side of the drawing sheet, the side surface of the window opening/closing section 103 is in contact with open position regulating section 209, and the window section 202 is completely opened, as shown in FIG. 11. Then, the rotation driving means for driving the rotation of the information medium 300 engages with a center hole 301 (actually, a turn table included in the medium rotation driving means enters into the rotation means entry portion 215 from one side of the cartridge and a clamper enters into the rotation means entry portion 215 from the other side of the cartridge, so that the information medium 300 is held by the turn table and the clamper) so as to drive the rotation of the information medium 300. Then, a head for sending/receiving user information signals for the information layer of the information medium 300 enters into the head entry portion 216 so that the head can be used to perform a recording/reproduction operation.
Next, the structure of the cartridge in the vicinity of the shutter pressing section 217 shown in FIGS. 9 to 11 will be described, with reference to FIGS. 12, 13A and 13B.
FIG. 12 is a plan view illustrating the cartridge with cutting lines in relation to FIGS. 13A and 13B. FIG. 13 is a cross-sectional view seen along the direction of arrow C, when the case member 200 is cut along a line C-C, which passes through the center of the rotation of the information medium 300 and which is perpendicular to the sliding direction. FIG. 13B is a cross-sectional view seen along the direction of arrow D, when the case member 200 is cut along a line D-D, which passes through an outer side portion of the center hole 301 within a range where the information medium 300 is held by the turn table and the clamper, and which is parallel to the line C-C shown in FIG. 13A.
In the cartridge, a direction along the rotation axis of the information medium 300 is referred to as a thickness direction (i.e. a direction towards the left and right sides of the drawing sheet), a direction perpendicular to the sliding sidewall 201 is referred to as a length direction (i.e. a direction towards the up and down sides of the drawing sheet), and a direction perpendicular to the length direction is referred to as a width direction.
With reference to FIGS. 13A and 13B, the dimensions are as follows:
The thickness of the eaves section 210 is 0.4 mm to 0.45 mm; The length of the eaves section 210 from the step portion 207 is 3.25 mm to 3.75 mm;
The gap between the eaves section 210 and the lower case section 206 along the thickness direction is 0.6 mm to 0.65 mm, wherein the eaves engagement section 104 is movably inserted into the gap; and
The thickness of the lower case section 206 is 1.9 mm to 2.1 mm; the length of the lower case section 206 from the step portion 207 shown in FIG. 13A is 9.05 mm to 9.25 mm.
It is difficult to simply define the length of the opening 218 from the step portion 207, since the length of the opening 218 from the step portion 207 varies depending on the length of the eaves section 210 and the precision level of the mold used in the injection molding process. However, the length of the opening 218 from the step portion 207 is set to be 0.5 mm to 1.0 mm longer than the projection plane of the eaves section 210 onto the lower case section 206.
The gap in the thickness direction between the lower case section 206 and the information medium 300 held by the turn table and the clamper is approximately 1.1 mm to 1.7 mm, although it may vary due to wobbling of the information medium 300.
In any state other than the state where the information medium 300 is held by the turn table and the camper, the surface of the information medium 300 is in contact with the storage surface of the medium storage section 211. As a result, the surface of the information layer for the recording/reproduction of the information signals is in contact with the surface of the storage surface of the medium storage section 211. This may adversely effect the recording/reproduction properties.
In order to prevent this adverse influence on the recording/reproduction properties, it is general to provide a mount rib (not shown) which restricts contact with the information layer, in the vicinity of the rotation means entry portion 215 and between the lower case section 206 and the information medium 300. The thickness of the lower case section 206 including the mount rib is 2.1 mm to 2.2 mm. As a result, the gap in the thickness direction between the mount rib and the Information medium 300 is narrowed by approximately 0.1 mm.
In addition, as shown in FIGS. 13A and 13B, the opening 218 is located at a portion of the lower case section 206 immediately below the eaves section 210.
FIG. 14 is a perspective view of the relevant parts of the cartridge shown in FIG. 13A. FIG. 14 shows a structure around the shutter pressing section 217 which is formed by the eaves section 210, the step portion 207 and the opening 218.
Reference 1: Japanese laid-open patent publication No. 2002-184151 (paragraphs 0002 and 0021; FIGS. 2 and 7).